Conventional web converting equipment uses some sort of transport mechanism for moving the web at high rates of speeds through a series of processing stations. Typically such processing stations include corrosive environments through which the web must be transported. For instance, in existing photographic film processors used to develop and fix photosensitive elements which are subjected to x-ray, visible, and other radiation, the web is transported via a series of rollers defining a web transport path through a sequence of processing stations including wash and dry stations.
Very often during processing, photosensitive media are coated with a magnetic layer to enable it to gather digital information. The magnetic layer often contains a small fraction of hard inorganic particles to facilitate cleaning of the magnetic head which are used for reading digital information in a read-out device. Photographic films are also coated with an "anti-staff" layer for dissipating static charges from the moving web. The anti-stat layers generally contain hard abrasive particles like tin oxide, antimony oxide, vanadium oxide, and the like.
Moreover, process and transport apparatus for photosensitive web or other media is another well known application requiring a web transport mechanism. Such equipment may include automatic processing of the media for thermal, ink jet, or silver halide-based photographic printing, and the like. The apparatus automatically transports sheets or webs or strips of photosensitive films, photosensitive papers, or specially coated papers or plain papers. For photosensitive elements, this apparatus transports from a feed end of a film transport path, through a sequence of chemical processing tanks in which the media is developed, fixed, and washed, and then through a dryer to a discharge or receiving end. The processing equipment typically has a fixed film (media) path length, so final image quality depends on factors including transport speed which determines length of time the media is in solution, and the temperature and composition of the processing chemicals.
Therefore, a need persists for an apparatus and method that makes use of an inorganic coated media bearing surface for conveying abrasive media, such apparatus having superior wear, abrasion, and corrosion resistance while being cost-effective and easy to manufacture. SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide an apparatus for conveying abrasive web, such as photographic media, of indeterminate length that utilizes compliant or semi-compliant media conveyance rollers.
Another object of the invention is to provide an apparatus for media conveyance rollers having a media bearing surface coated with semi-compliant materials having embedded therein hard wear and abrasion resistant inorganic particulate materials in a polymeric material matrix.
Yet another object of the invention is to provide an apparatus for conveying abrasive media that includes compliant media conveyance rollers having a media bearing surface coated with a thin, semi-compliant and hard inorganic coating.
Still another object of the invention is to provide an apparatus for conveying abrasive media that includes compliant media conveyance rollers having a media bearing surface comprising a hard, wear and abrasion resistant and electrically conductive particulate inorganic materials coating intended for dissipating static charges.
It is, therefore, a feature of the invention that a media bearing surface of the media for conveying abrasive media comprises an inorganic particulate coating in a polymeric matrix or a thin inorganic coating. The inorganic particulate coating may be certain metal oxides or it may be a sol-gel dispersion of select ceramics.
Accordingly, for accomplishing these and other objects, features and advantages of the invention, there is provided, in one aspect of the invention, an apparatus for conveying abrasive media of indeterminate length having a frame and closely spaced first and second rollers mounted for synchronous rotation in the frame. According to the invention, at least one of the first and second rollers has a media bearing surface comprising an inorganic particulate coating in a polymeric matrix, or a thin inorganic coating. Any sort of drive means, typically a motor, operably connected to any one of the first and second rollers rotates the roller and causes the other of first and second rollers to synchronously rotate therewith. Thus, when abrasive media of indeterminate length is disposed between the nip or close spacing between the rollers, the abrasive media is squeezed for movement between the rollers while in moving contact with the coated media bearing surface of at least one of the rollers.
In another aspect of the invention, a method of conveying abrasive media of indeterminate length includes providing the apparatus previously described and then disposing abrasive media in the nip defined by the close spacing between the first and second rollers. Any one of the first and second rollers may have a media bearing surface comprising an inorganic coating. Thus, the abrasive media, when disposed in the nip, is squeezed between the rollers on a coated media bearing surface of at least one of the rollers as the abrasive web is being conveyed between independent processing stations.
It is, therefore, an advantage of the invention that an apparatus for conveying abrasive media, such as photographic media, is simple to produce, assemble and operate. Another advantage of the invention is that the media bearing surface is sufficiently compliant to accommodate media of varying thickness. Further, the conveyance apparatus of the invention offers the advantage of providing sufficient friction to enable the movement of abrasive media between independent processing stations.